It may be desirable to know the number, distribution, and/or flow of people and/or devices in a given geographic area. This desire may stem from, but is not limited to, security concerns when organizing an outdoor concert, the dispatching of rescue teams in the event of a natural disaster, or the need to measure the flow of cars to detect and possibly prevent traffic jams. Knowing the number of people in a given geographic area may help in the cases mentioned above. For example, the organizers of a concert may use the distribution of the spectators to place their security forces. Information on traffic flow can be used to redirect people around congested areas, etc.
Current techniques for estimating the number of people in a particular geographical area are mainly based on direct visual inspection and counting. This may involve monitoring of an area via video camera, and/or the use of physical counters at gates. Visual inspection and estimation techniques suffer from the subjective nature of human estimates, making the estimate a function of the individual doing the inspection. In addition, visual inspection techniques are stymied in situations where the people are not in plain sight. Another drawback to visual inspection techniques, e.g., where remote cameras are used, is that they can require expensive dedicated infrastructure, such as camera mounts and communications links along a highway. Alternative techniques, e.g., automated techniques for estimating the number of people in an area that do not depend on visual inspection, are desirable.
In particular there is a need for techniques for counting people that eliminates the dependence on visual inspection, and eliminates variations due to the personal judgment of a person doing the counting.